Ilimiy is tiykarlari

The comparative design

With a comparative design, a study can be carried out either as an experiment or as a non-experiment. In the comparative experimental design, the study population is divided into the same number of groups as the number of treatments to be tested. For each group the baseline with respect to the dependent variable is established. The different treatment models are then introduced to the different groups. After a certain period, when it is assumed that the treatment models have had their effect, the ‘after’ observation is carried out to ascertain any change in the dependent variable. The degree of change is then compared to establish the effectiveness of the various interventions.

In the non-experimental comparative design, groups already receiving different interventions are identified, and only the post-observation with respect to the dependent variable is conducted. The pre-test data set is constructed either by asking the study population in each group to recall the required information relating to the period or by extracting such information from existing records. As each group is assumed to have the same baseline, the difference in the post-test observation is assumed to be because of the intervention.